Painting Structural Steel Indoors

Q. I’m the facilities manager of a plating shop that’s faced with repainting the structural steel components of a 12-year-old building. We plan to sand blast for surface prep. First, what media is recommended for blasting structural steel indoors? Is free silica in sand an issue only when blasting, or as a residual factor as well? What paint system is recommended for plating shop applications expecting a 20- to 30-year service life? Site ventilation is good and humidity is usually under control, but there are exceptional days. If more than one type of coating could perform, then what are the economics of the different systems? M. F.

 

A. As an organic chemist, I usually stay away from plating shops. That being said, you raise some interesting questions that I can only partially answer. So I won’t give you firm recommendations, but suggestions instead. My first thought would be to air-blast the surfaces to white metal using glass beads. I would prime the surfaces using an inorganic zinc-rich primer. Over that, I would apply either a two-component epoxy enamel or a vinyl enamel. I gleaned this information from the Steel Structures Painting Council (SSPC) Painting Manual Volume 1: Good Painting Practice. The manual suggests this finish system for use in chemical plants. However, I recommend you contact them and get the benefit of their latest information. They may have a finish system specifically tailored for plating shops.

They are located at Mellon Institute, listed there as Steel Structures Painting Council. Their address is SSPC, Mellon Institute, 4400 Fifth Avenue, Pittsburgh, PA 15213, and their phone number is 412-281-2331.